Lubricating composition including n-alkylated dianiline

ABSTRACT

A lubricating composition includes an oil of lubricating viscosity, an N-alkylated dianiline compound, and at least one of a) an ashless antioxidant, and b) an overbased calcium detergent. The ashless antioxidant may be selected from a diarylamine antioxidant, a phenolic antioxidant, and combinations thereof. The lubricating composition may contain less than 0.15 weight percent of phosphorus.

This application claims the priority of International Application PCT/US2017/066103, filed Dec. 13, 2017, and U.S. Provisional Application No. 62/439,246, filed Dec. 27, 2016, from which the PCT application claims priority, the disclosures of which are incorporated herein by reference, in their entireties.

BACKGROUND

The exemplary embodiment relates to additives for lubricating compositions and finds particular application in connection with N-alkylated dianilines for improved deposit control in as deposit boosters in internal combustion engines.

U.S. Pat. No. 3,779,923 describes alkylated methylenedianiline tars as antioxidants in lubricant compositions. The compounds are formed with a phosphorus-based catalyst.

U.S. Pat. No. 8,242,066 describes aniline compounds useful as ashless TBN sources for lubricating oil compositions that are compatible with fluoroelastomeric engine seal materials.

U.S. Pat. Nos. 4,100,082; 4,200,545; 4,320,021, and 4,663,063; 4,708.809 generally describe amino-phenol compounds as lubricating oil additives (e.g., dispersant/detergents).

One test for assessing deposit formation is the “Standard Test Method for Determination of Moderately High Temperature Piston Deposits by Thermo-Oxidation Engine Oil Simulation Test-TEOST MHT,” ASTM D7097-09. MHT TEOST, as it will be referred to herein, is a bench test that is designed to predict the deposit-forming tendencies of engine oil in the piston ring belt and upper piston crown area during service, and is one of the required test methods in Specification D 4485 to define API Category-Identified engine oils.

Some methylenedianiline compounds (MDAs) have been found to improve thermal oxidation performance in engine oils and to boost thin-film antioxidancy. However, formulating an engine oil for high performance on MHT TEOST can compromise performance in other key areas. For example, adding dispersants and detergents in large amounts can negatively impact the viscometric properties of the lubricating composition or seals performance.

It would be desirable for a lubricating composition to be able to provide good deposit control, both in fired engine tests and in bench tests such as MHT TEOST, while also providing other performance properties.

BRIEF DESCRIPTION

In accordance with one aspect of the exemplary embodiment, a lubricating composition includes an oil of lubricating viscosity, an N-alkylated dianiline compound and an oil of lubricating viscosity, and at least one of an ashless antioxidant and an overbased calcium detergent. The ashless antioxidant may be selected from a diarylamine antioxidant, a phenolic antioxidant, and combinations thereof. The lubricating composition includes less than 0.15 weight percent of phosphorus.

In accordance with another aspect of the exemplary embodiment, a method for reducing deposit formation in an internal combustion engine which includes lubricating the internal combustion engine with the lubricating composition.

In accordance with another aspect of the exemplary embodiment, a method for forming a lubricating composition includes forming an N-alkylated dianiline compound and combining the N-alkylated dianiline compound with an oil of lubricating viscosity and at least one of an ashless antioxidant and an overbased calcium detergent. The ashless antioxidant may be selected from a diarylamine antioxidant, a phenolic antioxidant, and combinations thereof. The lubricating composition includes less than 0.15 weight percent of phosphorus.

In various aspects of the exemplary embodiment:

The N-alkylated dianiline compound is hydrocarbylene-coupled.

The lubricating composition has a TBN of at least 4 mg KOH/g, as measured in accordance with ASTM D-2896.

The N-alkylated dianiline includes at least one N-alkyl group selected from cyclic alkyl groups, acyclic alkyl groups, and combinations thereof.

The N-alkyl group is a cyclohexyl group.

The N-alkylated dianiline is an N,N′-alkylated dianiline compound.

The N-alkylated dianiline compound is at least 0.10 weight percent of the lubricating composition, or at least 0.15 wt. %, or at least 0.2 wt. %, or at least 0.4 wt. % of the lubricating composition.

The N-alkylated dianiline compound is up to 4.0 weight percent of the lubricating composition, or up to 3 wt. %, or up to 1.5 wt. %, or up to 1.2 wt. % of the lubricating composition.

The N-alkylated dianiline compound is represented by the formula of any one of Structures I to IV and A1 to A8, described below, and mixtures thereof.

The hydrocarbylene group is a C₁-C₃ alkylene group.

The N-alkylated dianiline compound is selected from 4,4′-2-ethylhexylmethylenedianiline, 4,4′-cyclohexylmethylenedianiline, and mixtures thereof.

The oil of lubricating viscosity is at least 40 weight percent of the lubricating composition.

The ashless antioxidant is at least 0.1 weight % of the lubricating composition, or at least 0.2 wt. %, or at least 0.4 wt. %, or at least 0.6 wt. %, or up to 4 wt. %, or up to 1.2 wt. %, or up to 1 wt. % of the lubricating composition.

A ratio of the ashless antioxidant to the N-alkyl dianiline compound is from 20:1 to 1:20.

The ashless antioxidant includes a phenolic ester and a diarylamine.

The ashless antioxidant further includes a sulfurized olefin.

The overbased calcium detergent is selected from sulfonates, non-sulfur containing phenates, sulfur containing phenates, salixarates, salicylates, mixtures thereof, and borated equivalents thereof.

The overbased calcium detergent is present in an amount to deliver at least 2 mg KOH/g of total base number (TBN), as measured in accordance with ASTM D-2896, to the composition.

The overbased calcium detergent is least 0.01 wt. % or at least 0.1 wt. %, or at least 0.5 wt. %, or up to 3 wt. %, or up to 2 wt. % of the lubricating composition.

A ratio of calcium to magnesium in the lubricating composition, by weight, is at least 9:10.

The lubricating composition further includes a polyolefin succinimide dispersant, wherein the polyolefin of the polyolefin succinimide has a number average molecular weight of at least 300.

The lubricating composition further includes a zinc dialkyldithiophosphate.

The lubricating composition includes at least 0.02 weight percent of phosphorus.

The N-alkylated dianiline compound is a reaction product of a dianiline with at least one of an aldehyde and a ketone.

DETAILED DESCRIPTION

Aspects of the exemplary embodiment relate to lubricating compositions and to methods of lubricating an internal combustion engine. The lubrication composition includes an N-alkylated dianiline compound, an oil of lubricating viscosity, and at least one of an ashless antioxidant and a calcium overbased detergent. The ashless antioxidant may be selected from diarylamine antioxidants phenolic antioxidants, and mixtures thereof. The exemplary lubricating composition includes less than 0.15 wt. % phosphorus.

The N-Alkylated Dianiline

In the lubricating composition, the exemplary N-alkylated dianiline compound improves deposit performance, as measured by the MHT TEOST, while providing good TBN, without negatively impacting (and in some cases, improving) antioxidancy performance, when formulated for heavy duty diesel engine (HD) and passenger car engine applications. For example, in testing, N,N′-dicyclohexyl methylenedianiline (Cy MDA) is able to provide improvements in the MHT TEOST in both HD and passenger car formulations while also helping antioxidant performance, particularly under the Daimler Oxidation Test in a HD formulation.

In the exemplary N-alkylated dianiline compound, the two aromatic rings are hydrocarbylene coupled, e.g., with a C₁-C₃ hydrocarbylene group, in particular an alkylene group such as methylene, ethylene, methylmethylene, methylethylene, or dimethylmethylene. N-alkylated methylenedianiline compounds can be readily prepared. However, it is to be appreciated that other hydrocarbylene-coupled N-alkylated dianiline compounds are also contemplated.

By “N-alkylated” it is meant that an alkyl group is attached to the dianiline by one or both of the amine groups attached to the aromatic rings of the dianiline. Each of these N-alkyl groups may be a C₁-C₂₄ alkyl group, such as a C₃ or higher alkyl group, and may be selected from acyclic alkyl groups, cyclic alkyl groups, and combinations thereof. In the exemplary embodiment, each amine group of the dianiline has no more than one alkyl group. The exemplary N-alkylated methylenedianiline is an N, N-alkylated methylenedianiline, where both amine groups are alkylated.

The exemplary N, N-alkylated methylenedianiline contains no more than two aromatic rings linked by a hydrocarbylene group. While methods of generating the N-alkylated dianiline compound may result in structures having more than two aromatic rings linked by hydrocarbylene groups, in the exemplary embodiment, a molar ratio of these N-alkylated polyaromatic aniline compounds to the N-alkylated dianiline compound in the lubricating composition may be no greater than 1:10.

The N-alkylated hydrocarbylene-coupled dianiline compound may be represented by the formula shown in Structure I:

wherein R¹ and R² are independently selected from, or at least 3, or at least 4, or at least 5, or at least 6 carbon atoms, or up to 20, or up to 12, or up to 10, or up to 8 carbon atoms,

R³ and R⁴ are independently selected from hydrocarbyl groups of 1 to 6 carbon atoms,

each n is from 0 to 3, or 0 to 2, or 0 to 1, or 0, and

X represents a hydrocarbylene group, as described above, such as

—CH₂—.

In one embodiment, R¹ and R² are independently of the general form

where R⁵ and R⁶ are independently selected from H and alkyl groups of 1 to 20 carbon atoms or 1 to 12 carbon atoms, or 1 to 8 carbon atoms, and wherein at least one of R⁵ and R⁶ is not H, or wherein R⁵ and R⁶ together form a ring. In one embodiment, R⁵ is H or a C₁-C₃ alkyl group and R⁶ is a C₂-C₈ alkyl group, or a C₄-C₆ alkyl group. In another embodiment R⁵ and R⁶ together form a C₄-C₈ ring.

In one embodiment, the N-alkylated dianiline compound is represented by the formula:

The N-alkylated dianiline compound may be a 4,4′-N-alkylated dianiline compound represented by the formula:

Representative acyclic alkyl groups of the general formula C_(n)H_(2n+1) suitable for R¹ and R² include straight chain and branched chain alkyl groups, such as methyl, ethyl, n-propyl, n-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, hexadecyl, stearyl, icosyl, docosyl, tetracosyl, 1-methylpropyl, 2,2-dimethylpropyl, isobutyl, isopentyl, isohexyl, 2-ethylhexyl, isoheptyl, 2-ethylheptyl, 2-propylheptyl, isooctyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, isodecyl, 2-butyldecyl, 2-hexydecyl, 2-octyldodecyl, 2-hexyldodecyl, isotridecyl, 2-dodecylhexadecyl, 2-decyltetradecyl, 4-methyl-2-pentyl, 2-tetradecyloctyldecyl, monomethyl branched-isostearyl, and isomers and combinations thereof. In particular embodiments, the acyclic alkyl group is branched at the second or higher carbon, such as 2-ethylhexyl, 2-ethylheptyl, 2-ethyloctyl, and the like.

Representative cyclic alkyl groups of the general formula C_(n)H_(2n−1) suitable for R¹ and R² include cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl and combinations thereof.

Representative hydrocarbyl groups suitable for R³ and R⁴ include acyclic alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and mixtures and isomers thereof. In one embodiment n is 0, i.e., there are no R³ and R⁴ substituents on the aromatic rings.

Example N-alkylated dianiline compounds include compounds of formulas A-1 to A-8:

In specific embodiments, the N-alkylated dianiline compound is selected from 4,4′-2-cyclohexylmethylenedianiline (CY-MDI) (Formula A1), and 4,4′-2-ethylhexylmethylenedianiline (EHL-MDI) (Formula A2).

The N-alkylated dianiline compound may be present in the lubricating composition at a concentration of at least 0.1 wt. % and may be up to 5 wt. %. For example, the concentration of the compound may be at least 0.15 wt. %, or at least 0.4 wt. %, or at least 1.5 wt. %, or up to 5.0 wt. %, or up to 2.5 wt. % of the lubricating composition. The compound may also be present in a concentrate, alone or with other additives and with a lesser amount of oil. In a concentrate, the amount of the compound may be at least 2, or at least 3 times the concentration in the lubricating composition.

As used herein, TBN is measured according to ASTM D2896-15, Standard Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration, ASTM International, West Conshohocken, Pa., 2011, DOI: 10.1520/D2896-15.

In various aspects, the N-alkylated dianiline compound has a TBN of at least 50 mg of KOH/g, or at least 100 mg of KOH/g, as measured according to ASTM D2896.

In various aspects, the compound has a TBN of at least.

The lubricating composition of claim 1, wherein the composition has a TBN of at least 4 mg KOH/g, as measured in accordance with ASTM D-2896.

The N-alkylated dianiline compound is particularly effective at improving deposit performance in lubricating compositions which are low in phosphorus. In the exemplary lubricating composition, the phosphorus content of the lubricating composition is up to 0.15 wt. %, such as up to 0.12 wt. %, or up to 0.11 wt. %, or up to 0.08 wt. %, or up to 0.05 wt. %, or up to 0.04 wt. %, or up to 0.02 wt. %. The phosphorus content of the lubricating composition may be at least 0.01 wt. %, or at least 0.02 wt. %, or at least 0.03 wt. %. Suitable additives for providing the lubricating composition with such low levels of phosphorus include zinc dialkyldithiophosphates (ZDDPs), as described below.

Methods of Preparing the N-alkylated Dianiline Compound

The exemplary compounds may be prepared, for example, from dianilines, such as 4,4′-methylenedianiline, 2,4′-methylenedianiline, 2,2′-methylenedianiline, and mixtures thereof.

In one embodiment, N-alkylated dianiline compounds are prepared by reacting a dianiline with one or more aldehydes or ketones in a 1:2 or excess molar ratio in an alcohol solvent, such as methanol or toluene.

The aldehyde or ketone can be of the general formula:

where

corresponds to R¹ and R² above, at least one of R⁵ and R⁶ is not H.

In one embodiment, the aldehyde or ketone may be a C₂-C₁₂ aldehyde or ketone, such as a C₂-C₉ aldehyde, or a C₂-C₆ aldehyde or a C₃-C₁₀ ketone, or C₃-C₇ ketone.

Example ketones useful in forming the compound include methyl alkyl ketones and ethyl alkyl ketones of from 3-12 carbon atoms where the alkyl group may be alicyclic or cyclic. Examples of such ketones include those in which the alkyl portions are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclooctyl and as well as the various isomeric forms thereof. Examples of ketones include acetone, 2-butanone, 2-pentanone, 3-pentanone, 4-methyl-2-butanone, 2-hexanone, 4-methyl-2-hexanone, 4-heptanone, 5-methyl-2-hexanone, 5,6-dimethyl-2-hexanone, 5,5-dimethyl-2-hexanone, 4,5-dimethyl-2-hexanone, 4-ethyl-2-hexanone, 5-ethyl-2-hexanone, 4,5,5-trimethyl-2-hexanone, 2-heptanone, 3-heptanone, 5,5-dimethyl-2-heptanone, 4,5-dimethyl-2-heptanone, 5-ethyl-2-heptanone, 4-ethyl-2-heptanone, 2-octanone, 3-octanone, 4-octanone, 6-methyl-2-octanone, 7,7-dimethyl-2-octanone, 6-methyl-3-octanone, 6-ethyloctanone, 2-nonanone, 3-nonanone, 4-nonanone, 5-nonanone, 2-decanone, 3-decanone, 4-decanone, 5-decanone, cyclobutanone, cyclopentanone, cyclohexanone, methyl-cyclohexanones, ethyl-cyclohexanones, cycloheptanone, cyclooctanone, and the like.

As an example, 4,4′-methylenedianiline is reacted with an aldehyde/ketone in a 1:2 or excess molar ratio in a suitable solvent, such as toluene, at a temperature of over 100° C. Water formed in the reaction is removed. Once the reaction is complete, the solvent is removed. The product may be purified by redissolving it in a suitable solvent, such as methanol, and adding sodium borohydride. The mixture is poured into water and the product extracted using ethyl acetate. The solvent is removed yielding the purified product. An illustrative reaction scheme shown in Scheme 1:

where R⁵ and R⁶ are as described above.

N-alkylated dianiline compounds can also be prepared by reacting a methylenedianiline and one or more aldehydes or ketones in a 1:2 or excess molar ratio in the presence of hydrogen and a hydrogenation catalyst, such as platinum, palladium, cobalt or nickel, either as such or carried on a suitable support, such as carbon, in methanol solvent, as described, for example, in U.S. Pat. Nos. 2,045,574 and 3,779,923.

In general, the reaction results in mono-substitution of each —NH₂ group, although there may be a small amount of di-substituted compounds present.

A lubricating composition may be prepared by adding the N-alkylated dianiline compound and ashless antioxidant to an oil of lubricating viscosity, optionally in the presence of other performance additives (as described herein below), or by adding reagents for forming the N-alkylated dianiline compound to an oil of lubricating viscosity. The lubricating composition may further include additional performance additives, such as antioxidants, additional dispersants, antiwear agents, and friction modifiers. A method for forming a lubricating composition includes forming an N-alkylated dianiline compound and combining the N-alkylated dianiline compound with an oil of lubricating viscosity and at least one ashless antioxidant and/or overbased calcium detergent, to provide a lubricating composition comprising less than 0.15 weight percent of phosphorus.

The Ashless Antioxidant

The lubricating composition may include one or more ashless antioxidant(s) (AAO) selected from a diarylamine antioxidant, a phenolic antioxidant, and a mixture thereof. The AAO may be present in the lubricating composition at a concentration of at least 0.2 wt. %, such as at least 0.3 wt. %, or up to 5 wt. %, or up to 2.5 wt. %, or up to 2 wt. %, or up to 1 wt. %. A weight ratio of the AAO to the N-alkylated dianiline compound may be at least 1:20 or up to 20:1

Exemplary phenolic antioxidants useful herein include alkylated diphenylamine antioxidants, such as C₁-C₂₄ monoalkylated, dialkylated and polyalkylated diphenylamines, as described, for example, in U.S. Pat. Nos. 2,943,112; 4,824,601; 5,672,752; 6,204,412; 6,315,925; 6,355,839, and U.S. Pub. Nos. 2015/0307803 and 2016/0017252. Particularly useful are monoalkylated and dialkylated diphenylamines in which the alkyl group(s) include(s) at least 6 carbon atoms, such as at least 8, or at least 9 carbon atoms.

Exemplary phenolic antioxidants that may be used include C₇-C₉ branched alkyl esters of 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-benzenepropanoic acid, 2-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2-tert-butyl-5-methylphenol, 2,4-di-Cert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 2-tert-butyl-4-methoxyphenol, 3-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butyl-4-alkylphenols such as 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-alkoxyphenols such as 2,6-di-tert-butyl-4-methoxyphenol and 2,6-di-tert-butyl-4-ethoxyphenol, 3,5-di-tert-butyl-4-hydroxybenzylmercaptooctylacetate, alkyl-3-(3,5-di-tert-butyl-4-hyd roxyphenyl)propionates such as n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, n-butyl-3-(3,5-di-cert-butyl-4-hydroxyphenyl)propionate and 2′-ethylhexyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,6-di-tert-butyl-α-dimethylamino-p-cresol, 2,2′-methylene-bis(4-alkyl-6-tert-butylphenol) such as 2,2′-methylenebis(4-methyl-6-cert-butylphenol, and 2,2-methylenebis(4-ethyl-6-tert-butylphenol), bisphenols such as 4,4′-butylidenebis(3-methyl-6-tert-butylphenol, 4,4′-methylenebis(2,6-di-tert-butylphenol), 4,4′-bis(2,6-di-tert-butylphenol), 2,2-(di-p-hydroxyphenyl)propane, 2,2-bis(3,5-di-cert-butyl-4-hydroxyphenyl)propane, 4,4′-cyclohexylidenebis(2,6-tert-butylphenol), hexamethyleneglycol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethyleneglycolbis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], 2,2′-thio-[diethyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 3,9-bis{1,1-dimethyl-2-[3-(3-tert-butyl-4-hydroxy-5-methyl-phenyl)propionyloxy]ethyl}2,4,8,10-tetraoxaspiro[5,5]undecane, 4,4′-thiobis(3-methyl-6-tert-butylphenol) and 2,2′-thiobis(4,6-di-tert-butylresorcinol), polyphenols such as tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, bis-[3,3′-bis(4′-hydroxy-3′-tert-butylphenyl)butyric acid]glycol ester, 2-(3′,5′-di-tert-butyl-4-hydroxyphenyl)methyl-4-(2″,4″-di-tert-butyl-3″-hydroxyphenyl)methyl-6-tert-butylphenol and 2,6-bis(2′-hydroxy-3′-tert-butyl-5′-methylbenzyl)-4-methylphenol, p-t-butylphenol-formaldehyde condensates and p-t-butylphenol-acetaldehyde condensates.

Phenol-based antioxidants often contain a secondary butyl and/or a tertiary butyl group as a steric hindering group. The phenol group may be further substituted with a hydrocarbyl group (e.g., a linear or branched alkyl) and/or a bridging group linking to a second aromatic group.

Examples of particularly suitable hindered phenol antioxidants include 2,6-di-tert-butylphenol, 4,4′-methylenebis-(2,6-di-tert-butylphenol), 4-methyl-2,6-di-tert-butylphenol, 4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol, 4-butyl-2,6-di-tert-butylphenol, 4-dodecyl-2,6-di-tert-butylphenol, 2,2′-methylenebis(4-methyl-6-tert-butylphenol), 2,2′-methylenebis(4-ethyl-6-tert-butylphenol), as described, for example, in U.S. Pub. Nos. 2009/0111720, 2010/0269774, and 2012/0103290. In one embodiment, the hindered phenol antioxidant may be an ester, such as those described in U.S. Pat. No. 6,559,105, such as an alkyl alcohol esters of 3-(4-hydroxy-3,5-di-tert-butyl-phenyl)propionic acid. One such hindered phenol ester is sold as Irganox™ L-135, obtainable from Ciba.

The phenolic antioxidant, where present in the lubricating composition, may be at least 0.1 weight % of the lubricating composition, or at least 0.5 wt. %, or at least 1.5 wt. %, or at least 2.5 wt. %, and may be up to 5 wt. %, such as up to 4 wt. %, or up to 3 wt. % of the lubricating composition.

Examples of alkylated diphenylamines useful herein include those of the general formula:

where each of R⁷, R⁸, R⁹ and R¹⁰, is selected from H and C₈-C₂₄ or C₈-C₁₂ alkyl groups, and wherein at least one of R⁷, R⁸, R⁹, and R¹⁰ is not H. In one embodiment, R⁸ and R¹⁰ (and optionally also R⁹) are not H. Para-substitution by the alkyl group is common.

Example alkylated diphenylamines include dinonyl diphenylamine, nonyl diphenylamine, octyl diphenylamine, dioctyl diphenylamine, dodecyl diphenylamine, decyl diphenylamine, and mixtures thereof.

Methods for producing monoalkylated diphenylamines are described in U.S. Pat. No. 5,672,752. Methods for selectively producing p,p′-di-alkylated diphenylamines are described in U.S. Pub. No. 2016/0017252.

Other exemplary diarylamine antioxidants include alkylated phenylnaphthylamines of the general form:

where each of R⁷, R⁸ are as defined above and at least one of R⁷ and R⁸ is not H.

Example alkylated phenylnaphthylamines include octyl, dioctyl, nonyl, dinonyl, decyl and dodecyl phenylnaphthylamines, such as N-(Dodecylphenyl)naphthalen-1-amine:

In one embodiment, a ratio of the diarylamine to the N-alkyl dianiline compound is from 20:1 to 1:20.

The alkylated diarylamine, where present in the lubricating composition, may be at least 0.1 weight % of the lubricating composition, or at least 0.2 wt. %, or at least 0.4 wt. %, or at least 0.5 wt. %, or at least 1.0 wt. %, or at least 2.5 wt. %, and may be up to 5 wt. %, such as up to 2.5 wt. %, or up to 1.5 wt. % of the lubricating composition.

Mixtures of phenolic and/or alkylated diarylamine antioxidants may be employed. When both an alkylated diarylamine and phenolic antioxidant are used, the combined amount of ashless antioxidant may be at least 0.1 weight % of the lubricating composition, or at least 0.8 wt. %, or at least 1.5 wt. %, or at least 3 wt. %, and may be up to 5 wt. %, such as up to 4 wt. %, or up to 3.5 wt. % of the lubricating composition.

Overbased Calcium Detergent

In one embodiment, the lubricating composition includes one or more overbased calcium detergents. In one embodiment, the lubricating composition includes an alkaline earth metal overbased detergent in an amount sufficient to deliver at least 2 mg KOH/g of total base number (TBN), as measured in accordance with ASTM D-2896-15, to the lubricating composition.

The overbased calcium detergent may be chosen from sulfonates, non-sulfur containing phenates, sulfur containing phenates, salixarates, salicylates, and mixtures thereof, or borated equivalents thereof. The overbased detergent may be borated with a borating agent such as boric acid.

The overbased calcium-containing detergent may also include “hybrid” detergents formed with mixed surfactant systems including phenate and/or sulfonate components, e.g., phenate/salicylates, sulfonate/phenates, sulfonate/salicylates, sulfonates/phenates/salicylates, as described, for example, in U.S. Pat. Nos. 6,429,178; 6,429,179; 6,153,565; and 6,281,179. Where a hybrid sulfonate/phenate detergent is employed, the hybrid detergent can be considered equivalent to amounts of distinct phenate and sulfonate detergents introducing like amounts of phenate and sulfonate soaps, respectively.

Example overbased calcium-containing detergents include calcium salts of sulfonates, phenates (including sulfur-containing and non-sulfur containing phenates), salixarates and salicylates. Such overbased sulfonates, salixarates, phenates and salicylates may have a total base number of 120 to 700, or 250 to 600, or 300 to 500 (on an oil free basis).

Overbased calcium sulfonates, salixarates, phenates and salicylates typically have a total base number of 120 to 700 TBN. Overbased sulfonates typically have a total base number of 120 to 700, or 250 to 600, or 300 to 500 (on an oil free basis).

By “overbased,” it is meant that the calcium is in excess of stoichiometric amounts with respect to the soap counterion (e.g., sulfonate). The overbased calcium detergent may have a metal: counterion ratio of at least 3:1, or at least 4:1, or at least 6:1.

Example sulfonate detergents include linear and branched alkylbenzene sulfonate detergents, and mixtures thereof, which may have a metal ratio of at least 8, as described, for example, in U.S. Pub. No. 2005065045. Linear alkyl benzenes may have the benzene ring attached anywhere on the linear chain, usually at the 2, 3, or 4 position, or be mixtures thereof. Linear alkylbenzene sulfonate detergents may be particularly useful for assisting in improving fuel economy.

In one embodiment, the alkylbenzene sulfonate detergent may be a branched alkylbenzene sulfonate, a linear alkylbenzene sulfonate, or mixtures thereof.

In one embodiment, the lubricating composition may be free of linear alkylbenzene sulfonate detergent. The sulfonate detergent may be a calcium salt of one or more oil-soluble alkyl toluene sulfonate compounds as disclosed in U.S. Pub. No. 20080119378.

The lubricating composition may include at least 0.01 wt. % or at least 0.1 wt. %, or at least 0.5 wt. %, of overbased calcium detergent, and in some embodiments, up to 3 wt. %, or up to 2 wt. % overbased calcium detergent(s).

Oil of Lubricating Viscosity

The lubricating composition may include the oil of lubricating viscosity as a minor or major component thereof, such as at least 5 wt. %, or at least 10 wt. %, or at least 20 wt. %, or at least 30 wt. %, or at least 40 wt. %, or at least 60 wt. %, or at least 80 wt. %, or up to 98 wt. %, or up to 95 wt. %, of the lubricating composition.

The amount of the oil of lubricating viscosity present may be typically the balance remaining after subtracting from 100 wt. %, the sum of the amount of the compound and antioxidant, as described above and any other performance additives.

Suitable oils include natural and synthetic oils, oil derived from hydrocracking, hydrogenation, and hydrofinishing, unrefined, refined, re-refined oils or mixtures thereof. Unrefined, refined and re-refined oils, and natural and synthetic oils are described, for example, in WO 2008/147704 and U.S. Pub. No. 2010/197536. Synthetic oils may also be produced by Fischer-Tropsch reactions and typically may be hydroisomerized Fischer-Tropsch hydrocarbons or waxes. Oils may be prepared by a Fischer-Tropsch gas-to-liquid synthetic procedure as well as other gas-to-liquid procedures.

Oils of lubricating viscosity may also be defined as specified in April 2008 version of “Appendix E—API Base Oil Interchangeability Guidelines for Passenger Car Motor Oils and Diesel Engine Oils”, section 1.3 Sub-heading 1.3. “Base Stock Categories”. The API Guidelines are also summarized in U.S. Pat. No. 7,285,516. The five base oil groups are as follows: Group I (sulfur content >0.03 wt. %, and/or <90 wt. % saturates, viscosity index 80-120); Group II (sulfur content <0.03 wt. %, and >90 wt. % saturates, viscosity index 80-120); Group III (sulfur content <0.03 wt. %, and >90 wt. % saturates, viscosity index >120); Group IV (all polyalphaolefins (PAOs)); and Group V (all others not included in Groups I, II, III, or IV). The exemplary oil of lubricating viscosity includes an API Group I, Group II, Group III, Group IV, Group V oil, or mixtures thereof. In some embodiments, the oil of lubricating viscosity is an API Group I, Group II, Group III, or Group IV oil, or mixtures thereof. In some embodiments, the oil of lubricating viscosity is an API Group I, Group II, or Group III oil, or mixture thereof. In one embodiment the oil of lubricating viscosity may be an API Group II, Group III mineral oil, a Group IV synthetic oil, or mixture thereof. In some embodiments, at least 5 wt. %, or at least 10 wt. %, or at least 20 wt. %, or at least 40 wt. % of the lubricating composition is a polyalphaolefin (Group IV).

The lubricating composition disclosed herein may have a SAE viscosity grade of XW-Y, wherein X may be 0, 5, 10 or 15; and Y may be 16, 20, 30 or 40.

The oil of lubricating viscosity may have a kinematic viscosity of up to 12 mm²/s or up to 8 mm²/s (cSt) at 100° C. and can be at least 12 mm²/s at 100° C., and in other embodiments at least 3.5 mm²/s. As used herein, kinematic viscosity is determined at 100° C. by ASTM D445-14, “Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity),” ASTM International, West Conshohocken, Pa., 2003, DOI: 10.1520/D0445-14 and may be referred to as KV_100.

The viscosity grade of the oil depends on the end use. For passenger car and diesel engines, the viscosity grade may be SAE-5W-30, SAE 10W-30 or SAE 15W-40. The base oil may be a blend of two or more fractions having different oligomer distributions. A fraction rich in lower oligomers is typically blended with a fraction rich in higher oligomers to achieve the desired oligomer distribution. However, any combination of fractions which will yield a composite having the required distribution of oligomers is acceptable. The fractions employed for such blending may be different distillation cuts from the same process or may be obtained from entirely different oligomerization processes. A single fraction may be used to produce different multigrade oils, e.g. SAE 10W-30 and SAE 15W-40 oils. The composite obtained after blending can be hydrogenated or the individual fractions can be hydrogenated before they are blended.

For 2-stroke marine diesel engines the viscosity grade may be from SAE-40 to SAE-60, which corresponds to a KV_100 of 12.5 to 26 mm²/s. SAE-50 grade oils, for example, have a KV_100 of 16.3-21.9 mm²/s. Cylinder oils for 2-stroke marine diesel engines may be formulated to achieve a KV_100 of 19 to 21.5 mm²/s. This viscosity can be obtained by a mixture of additives and base oils, for example containing mineral bases of Group I such as Neutral Solvent (for example 500 NS or 600 NS) and Bright Stock bases. Any other combination of mineral or synthetic bases or bases of vegetable origin having, in mixture with the additives, a viscosity compatible with the grade SAE 50 can be used.

As an example, an oil formulation suited to use as a cylinder lubricant for low-speed 2-stroke marine diesel engines contains 18 to 25 wt. % of a Group I base oil of a BSS type (distillation residue, with a KV_100 of 28-32 mm²/s, with a density at 15° C. of 895-915 kg/m³), and 50 to 60 wt. % of a Group I base oil of a SN 600 type (distillate, with a density at 15° C. of 880-900 kg/m³, with a KV_100 of about 12 mm²/s).

In certain embodiments, the lubricating composition may contain synthetic ester base fluids. Synthetic esters may have a kinematic viscosity measured at 100° C. of 2.5 mm²/s to 30 mm²/s. In one embodiment, the lubricating composition comprises less than 50 wt. % of a synthetic ester base fluid with a KV_100 of at least 5.5 mm²/s, or at least 6 mm²/s, or at least 8 mm²/s.

Exemplary synthetic oils include poly-alpha olefins, polyesters, poly-acrylates, and poly-methacrylates, and co-polymers thereof. Example synthetic esters include esters of a dicarboxylic acid (e.g., selected from phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, and alkenyl malonic acids) with an alcohol (e.g., selected from butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, and propylene glycol). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid.

Esters useful as synthetic oils also include those made from C₅ to C₁₂ monocarboxylic acids and polyols and from polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol. Esters can also be monoesters, such as are available under the trade name Priolube 1976™ (C₁₈-alkyl-COO—C₂₀ alkyl).

Synthetic ester base oils may be present in the lubricating composition in an amount less than 50 wt. % of the composition, or less than 40 weight %, or less than 35 weight %, or less than 28 weight %, or less than 21 weight %, or less than 17 weight %, or less than 10 weight %, or less than 5 weight % of the composition. In one embodiment, the lubricating composition is free of, or substantially free of, a synthetic ester base fluid having a KV_100 of at least 5.5 mm²/s.

Example natural oils include animal and vegetable oils, such as long chain fatty acid esters. Examples include linseed oil, sunflower oil, sesame seed oil, beef tallow oil, lard oil, palm oil, castor oil, cottonseed oil, corn oil, peanut oil, soybean oil, olive oil, whale oil, menhaden oil, sardine oil, coconut oil, palm kernel oil, babassu oil, rape oil, and soya oil.

The amount of the oil of lubricating viscosity present is typically the balance remaining after subtracting from 100 weight % the sum of the amount of the exemplary N-alkylated methylenedianiline compound and the other performance additives.

Other Performance Additives

In addition to the exemplary N-alkylated dianiline compound(s) disclosed herein, the lubricating composition may further include one or more of the following additional performance additives: antioxidants (different from above), dispersants, viscosity modifiers, antiwear/antiscuffing agents, metal deactivators, friction modifiers, extreme pressure agents, foam inhibitors, demulsifiers, pour point depressants, corrosion inhibitors, seal swelling agents, TBN boosters, and the like. The additional performance additive(s) may be suited to providing the performance properties of a fully formulated lubricating composition, e.g., a passenger car or HD engine lubricant.

A. Detergents

The lubricating composition optionally further includes at least one detergent, in addition to the overbased calcium detergent discussed above. Exemplary detergents useful herein include overbased metal-containing detergents, where the metal is other than calcium.

The metal of the metal-containing detergent may be zinc, sodium, barium, or magnesium. In one embodiment, the lubricating composition includes an alkaline earth metal overbased detergent in an amount sufficient to deliver at least 2 mg KOH/g of total base number (TBN), as measured in accordance with ASTM D-2896-15, to the lubricating composition.

The overbased metal-containing detergent may be chosen from sulfonates, non-sulfur containing phenates, sulfur containing phenates, salixarates, salicylates, and mixtures thereof, or borated equivalents thereof. The overbased detergent may be borated with a borating agent such as boric acid.

The overbased metal-containing detergent may also include “hybrid” detergents formed with mixed surfactant systems including phenate and/or sulfonate components, e.g., phenate/salicylates, sulfonate/phenates, sulfonate/salicylates, sulfonates/phenates/salicylates, as described, for example, in U.S. Pat. Nos. 6,429,178; 6,429,179; 6,153,565; and 6,281,179. Where a hybrid sulfonate/phenate detergent is employed, the hybrid detergent can be considered equivalent to amounts of distinct phenate and sulfonate detergents introducing like amounts of phenate and sulfonate soaps, respectively.

Example overbased metal-containing detergents include zinc, sodium, and magnesium salts of sulfonates, phenates (including sulfur-containing and non-sulfur containing phenates), salixarates and salicylates. Such overbased sulfonates, salixarates, phenates and salicylates may have a total base number of 120 to 700, or 250 to 600, or 300 to 500 (on an oil free basis).

Typically, an overbased metal-containing detergent may be a zinc, sodium, or magnesium salt of a sulfonate, a phenate, sulfur-containing phenate, salixarate or salicylate. Overbased sulfonates, salixarates, phenates and salicylates typically have a total base number of 120 to 700 TBN. Overbased sulfonates typically have a total base number of 120 to 700, or 250 to 600, or 300 to 500 (on an oil free basis).

The overbased metal-containing detergent may be alkali metal or alkaline earth metal salts. In one embodiment, the overbased detergent may be sodium salts, calcium salts, magnesium salts, or mixtures thereof of the phenates, sulfur-containing phenates, sulfonates, salixarates and salicylates. In one embodiment, the overbased detergent is a calcium detergent, a magnesium detergent or mixtures thereof. In one embodiment, the overbased calcium detergent may be present in an amount to deliver at least 500 ppm calcium by weight and no more than 3000 ppm calcium by weight, or at least 1000 ppm calcium by weight, or at least 2000 ppm calcium by weight, or no more than 2500 ppm calcium by weight to the lubricating composition. In one embodiment, the overbased detergent may be present in an amount to deliver no more than 500 ppm by weight of magnesium to the lubricating composition, or no more than 330 ppm by weight, or no more than 125 ppm by weight, or no more than 45 ppm by weight. In one embodiment, the lubricating composition is essentially free of (i.e., contains less than 10 ppm) magnesium resulting from the overbased detergent. In one embodiment, the overbased detergent may be present in an amount to deliver at least 200 ppm by weight of magnesium, or at least 450 ppm by weight magnesium, or at least 700 ppm by weight magnesium to the lubricating composition. In one embodiment, both calcium and magnesium containing detergents may be present in the lubricating composition. Calcium and magnesium detergents may be present such that the weight ratio of calcium to magnesium is 10:1 to 1:10, or 8:3 to 4:5, or 1:1 to 1:3. In one embodiment, the overbased detergent is free of or substantially free of sodium.

The overbased sulfonate detergent may have a metal ratio of 12 to less than 20, or 12 to 18, or 20 to 30, or 22 to 25.

Example sulfonate detergents include linear and branched alkylbenzene sulfonate detergents, and mixtures thereof, which may have a metal ratio of at least 8, as described, for example, in U.S. Pub. No. 2005065045. Linear alkyl benzenes may have the benzene ring attached anywhere on the linear chain, usually at the 2, 3, or 4 position, or be mixtures thereof. Linear alkylbenzene sulfonate detergents may be particularly useful for assisting in improving fuel economy.

In one embodiment, the alkylbenzene sulfonate detergent may be a branched alkylbenzene sulfonate, a linear alkylbenzene sulfonate, or mixtures thereof.

In one embodiment, the lubricating composition may be free of linear alkylbenzene sulfonate detergent. The sulfonate detergent may be a metal salt of one or more oil-soluble alkyl toluene sulfonate compounds as disclosed in U.S. Pub. No. 20080119378.

The lubricating composition may include at least 0.01 wt. % or at least 0.1 wt. %, detergent, and in some embodiments, up to 2 wt. %, or up to 1 wt. % detergent.

B. Antioxidants

The lubricating composition optionally further includes at least one antioxidant, in addition to the AAOs listed above. Exemplary antioxidants useful herein include sulfurized olefins. Examples of suitable olefins that may be sulfurized to form the sulfurized olefin include propylene, butylene, isobutylene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, undecene, tridecene, tetradecene, pentadecene, hexadecene, heptadecene, octadecene, nonadecene, eicosene, and mixtures thereof. In one embodiment, hexadecene, heptadecene, octadecene, nonadecene, eicosene, or mixtures thereof and their dimers, trimers and tetramers are especially useful olefins.

Alternatively, the olefin may be a Diels-Alder adduct of a diene such as 1,3-butadiene and an unsaturated ester, such as, butyl acrylate. Another class of sulfurized olefin includes fatty acids and their esters. The fatty acids are often obtained from vegetable oil or animal oil; and typically contain 4 to 22 carbon atoms. Examples of suitable fatty acids and their esters include triglycerides, oleic acid, linoleic acid, palmitoleic acid, and mixtures thereof. The fatty acids may be obtained from lard oil, tall oil, peanut oil, soybean oil, cottonseed oil, sunflower seed oil or mixtures thereof. In one embodiment fatty acids and/or ester are mixed with olefins. When present, the lubricating composition may include at least 0.1 wt. % or at least 0.5 wt. %, or at least 1 wt. % antioxidant, and in some embodiments, up to 3 wt. %, or up to 2.75 wt. %, or up to 2.5 wt. %, or up to 1.2 wt. % of such additional antioxidants.

C. Dispersants

The lubricating composition optionally further includes at least one dispersant other than the exemplary compound. Exemplary dispersants include succinimide dispersants, Mannich dispersants, succinamide dispersants, and polyolefin succinic acid esters, amides, and ester-amides, and mixtures thereof.

The succinimide dispersant may be derived from an aliphatic polyamine, or mixtures thereof. The aliphatic polyamine may be an ethylenepolyamine, a propylenepolyamine, a butylenepolyamine, or a mixture thereof. In one embodiment the aliphatic polyamine may be an ethylenepolyamine. In one embodiment the aliphatic polyamine may be chosen from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyamine still bottoms, and mixtures thereof.

In one embodiment, the dispersant may be a polyolefin succinic acid ester, amide, or ester-amide. A polyolefin succinic acid ester-amide may be a polyisobutylene succinic acid reacted with an alcohol (such as pentaerythritol) and a polyamine as described above. Example polyolefin succinic acid esters include polyisobutylene succinic acid esters of pentaerythritol and mixture thereof.

The dispersant may be an N-substituted long chain alkenyl succinimide. An example of an N-substituted long chain alkenyl succinimide is polyisobutylene succinimide. Typically the polyisobutylene from which polyisobutylene succinic anhydride is derived has a number average molecular weight of at least 300, or at least 350, or at least 500, or at least 550, or at least 750, and can be up to 5000, or up to 3000, or up to 2500. Such succinimides can be formed, for example, from high vinylidene polyisobutylene and maleic anhydride. Succinimide dispersants and their preparation are disclosed, for example, in U.S. Pat. Nos. 3,172,892, 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170, 3,467,668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, Re 26,433, and 6,165,235, and 7,238,650 and EP Patent Application 0 355 895 A.

The exemplary dispersants may also be post-treated by conventional methods by a reaction with any of a variety of agents. Among these are boron compounds (such as boric acid), urea, thiourea, dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones, carboxylic acids, such as terephthalic acid, hydrocarbon-substituted succinic anhydrides, maleic anhydride, nitriles, epoxides, and phosphorus compounds. In one embodiment the post-treated dispersant is borated. In one embodiment the post-treated dispersant is reacted with dimercaptothiadiazoles. In one embodiment the post-treated dispersant is reacted with phosphoric or phosphorous acid. In one embodiment the post-treated dispersant is reacted with terephthalic acid and boric acid (as described in U.S. Pub. No. 2009/0054278.

Dispersant viscosity modifiers (DVMs) are dispersants which provide both dispersancy and viscosity modification. Example DVMs are made from polymers such as an olefin polymer (e.g., ethylene propylene copolymer) and/or vinyl aromatic polymers (e.g., polystyrene) that have been radically grafted with an ethylenically unsaturated carboxylic acid material, such as maleic anhydride which is functionalized with one or more amines and/or a pendent functional group which has sulfonate functionality. DVMs of this type are disclosed, for example, in U.S. Pat. Nos. 4,863,623; 5,264,140; 5,409,623; 6,107,257; 6,107,258; 6,117,825; U.S. Pub. Nos. 2012/0178656; 2012/0178659; 2009/0305923, and WO 2016044262.

When present, the lubricating composition may include at least 0.01 wt. %, or at least 0.1 wt. %, or at least 0.5 wt. %, or at least 1 wt. % dispersant, and in some embodiments, up to 20 wt. %, or up to 15 wt. %, or up to 10 wt. %, or up to 6 wt. % or up to 3 wt. % dispersant.

D. Anti-Wear Agents

The lubricating composition optionally further includes at least one antiwear agent. Examples of suitable antiwear agents suitable for use herein include titanium compounds, tartrates, tartrimides, oil soluble amine salts of phosphorus compounds, sulfurized olefins, metal dihydrocarbyldithiophosphates (such as zinc dialkyldithiophosphates (ZDDPs)), phosphites (such as dibutyl phosphite), phosphonates, thiocarbamate-containing compounds, such as thiocarbamate esters, thiocarbamate amides, thiocarbamic ethers, alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamyl) disulfides. The antiwear agent may in one embodiment include a tartrate or tartrimide, as described in U.S. Pub. Nos. 2006/0079413; 2006/0183647; and 2010/0081592. The tartrate or tartrimide may contain alkyl-ester groups, where the sum of carbon atoms on the alkyl groups is at least 8. The antiwear agent may, in one embodiment, include a citrate as disclosed in U.S. Pub. No. 20050198894.

When present, the lubricating composition may include at least 0.01 wt. %, or at least 0.1 wt. %, or at least 0.5 wt. % antiwear agent, and in some embodiments, up to 3 wt. %, or up to 1.5 wt. %, or up to 0.9 wt. antiwear agent.

In one embodiment, the lubricating composition is free or substantially free of phosphorus-containing antiwear agents. For example phosphorus-containing antiwear agents are present, if at all, in an amount which enables the lubricating composition to have no more than 0.15 wt. % phosphorus, or up to 1.1 wt. % phosphorus, or up to 0.8 wt. % phosphorus. For example, C3/6 mixed secondary ZDDP's may be present at up to 1.2 wt. %, or up to 1 wt. %, or up to 0.5 wt. %.

E. Oil Soluble Titanium Compounds

The lubricating composition may include one or more oil-soluble titanium compounds, which may function as antiwear agents, friction modifiers, antioxidants, deposit control additives, or more than one of these functions. Example oil-soluble titanium compounds are disclosed in U.S. Pat. No. 7,727,943 and U.S. Pub. No. 2006/0014651. Example oil soluble titanium compounds include titanium (IV) alkoxides, such as titanium (IV) isopropoxide and titanium (IV) 2-ethylhexoxide. Such alkoxides may be formed from a monohydric alcohol, a vicinal 1,2-diol, a polyol, or mixture thereof. The monohydric alkoxides may have 2 to 16, or 3 to 10 carbon atoms. In one embodiment, the titanium compound comprises the alkoxide of a vicinal 1,2-diol or polyol. 1,2-vicinal diols include fatty acid mono-esters of glycerol, where the fatty acid may be, for example, oleic acid. Other example oil soluble titanium compounds include titanium carboxylates, such as titanium neodecanoate.

When present in the lubricating composition, the amount of oil-soluble titanium compounds is included as part of the antiwear agent.

F. Extreme Pressure (EP) Agents

The lubricating composition may include an extreme pressure agent. Example extreme pressure agents that are soluble in the oil include sulfur- and chlorosulfur-containing EP agents, dimercaptothiadiazole or CS₂ derivatives of dispersants (typically succinimide dispersants), derivative of chlorinated hydrocarbon EP agents and phosphorus EP agents. Examples of such EP agents include chlorinated wax; sulfurized olefins (such as sulfurized isobutylene), hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazoles and oligomers thereof, organic sulfides and polysulfides, such as dibenzyl disulfide, bis-(chlorobenzyl) disulfide, dibutyl tetrasulfide, sulfurized methyl ester of oleic acid, sulfurized alkylphenol, sulfurized dipentene, sulfurized terpene, and sulfurized Diels-Alder adducts; phosphosulfurized hydrocarbons such as the reaction product of phosphorus sulfide with turpentine or methyl oleate; phosphorus esters, such as di-hydrocarbon and tri-hydrocarbon phosphites, e.g., dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite; dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite and polypropylene substituted phenol phosphite; metal thiocarbamates, such as zinc dioctyldithiocarbamate and barium heptylphenol diacid; amine salts of alkyl and dialkylphosphoric acids or derivatives including, for example, the amine salt of a reaction product of a dialkyldithiophosphoric acid with propylene oxide and subsequently followed by a further reaction with P₂O₅; and mixtures thereof. Some useful extreme pressure agents are described in U.S. Pat. No. 3,197,405.

When present, the lubricating composition may include at least 0.01 wt. %, or at least 0.1 wt. %, or at least 0.5 wt. % extreme pressure agent, and in some embodiments, up to 3 wt. %, or up to 1.5 wt. %, or up to 0.9 wt. % of the extreme pressure agent.

G. Foam Inhibitors

The lubricating composition may include a foam inhibitor. Foam inhibitors that may be useful in the lubricant composition include polysiloxanes; copolymers of ethyl acrylate and 2-ethylhexylacrylate and optionally vinyl acetate; demulsifiers including fluorinated polysiloxanes, trialkyl phosphates, polyethylene glycols, polyethylene oxides, polypropylene oxides and (ethylene oxide-propylene oxide) polymers.

H. Viscosity Modifiers

The lubricating composition may include a viscosity modifier. Viscosity modifiers (also sometimes referred to as viscosity index improvers or viscosity improvers) useful in the lubricant composition are usually polymers, including polyisobutenes, polymethacrylates (PMA) and polymethacrylic acid esters, diene polymers, polyalkylstyrenes, esterified styrene-maleic anhydride copolymers, hydrogenated alkenylarene-conjugated diene copolymers and polyolefins also referred to as olefin copolymer or OCP. PMAs are prepared from mixtures of methacrylate monomers having different alkyl groups. The alkyl groups may be either straight chain or branched chain groups containing from 1 to 18 carbon atoms. Most PMAs are viscosity modifiers as well as pour point depressants. In one embodiment, the viscosity modifier is a polyolefin comprising ethylene and one or more higher olefin, such as propylene.

When present, the lubricating composition may include at least 0.01 wt. %, or at least 0.1 wt. %, or at least 0.3 wt. %, or at least 0.5 wt. % polymeric viscosity modifiers, and in some embodiments, up to 10 wt. %, or up to 5 wt. %, or up to 2.5 wt. % polymeric viscosity modifiers.

I. Corrosion Inhibitors and Metal Deactivators

The lubricating composition may include a corrosion inhibitor. Corrosion inhibitors/metal deactivators that may be useful in the exemplary lubricating composition include fatty amines, octylamine octanoate, condensation products of dodecenyl succinic acid or anhydride, and a fatty acid such as oleic acid with a polyamine, derivatives of benzotriazoles (e.g., tolyltriazole), 1,2,4-triazoles, benzimidazoles, 2-alkyldithiobenzimidazoles and 2-alkyldithiobenzothiazoles.

J. Pour Point Depressants

The lubricating composition may include a pour point depressant. Pour point depressants that may be useful in the exemplary lubricating composition include polyalphaolefins, esters of maleic anhydride-styrene copolymers, polymethacrylates, polyacrylates, and polyacrylamides.

K. Friction Modifiers

The lubricating composition may include a friction modifier. Friction modifiers that may be useful in the exemplary lubricating composition include fatty acid derivatives such as amines, esters, epoxides, fatty imidazolines, condensation products of carboxylic acids and polyalkylene-polyamines and amine salts of alkylphosphoric acids. The friction modifier may be an ash-free friction modifier. Such friction modifiers are those which typically not produce any sulfated ash when subjected to the conditions of ASTM D 874 (see ASTM D874-13a, “Standard Test Method for Sulfated Ash from Lubricating Oils and Additives,” ASTM International, West Conshohocken, Pa., 2013). An additive is referred to as “non-metal containing” if it does not contribute metal content to the lubricant composition. As used herein the term “fatty alkyl” or “fatty” in relation to friction modifiers means a carbon chain having 8 to 30 carbon atoms, typically a straight carbon chain.

The amount of the ash-free friction modifier in a lubricant may be 0.1 to 3 wt. % (or 0.12 to 1.2 or 0.15 to 0.8 wt. %). The material may also be present in a concentrate, alone or with other additives and with a lesser amount of oil. In a concentrate, the amount of material may be two to ten times the above concentration amounts.

In one embodiment, the ash-free friction modifier may be represented by the formula:

where D and D′ are independently selected from —O—, >NH, >NR²³, an imide group formed by taking together both D and D″ groups and forming a R²¹—N< group between two >C═O groups; E is selected from >CH₂, >CHR²⁶, >CR²⁶R²⁷, >C(OH)(CO₂R²²), >C(CO₂R²²)₂, and >CHOR²⁸; where R²⁴ and R²⁵ are independently selected from >CH₂, >CHR²⁶, >CR²⁶R²⁷, >C(OH)(CO₂R²²), and >CHOR²⁸; q is 0 to 10, with the proviso that when q=1, E is not >CH₂, and when n=2, both Es are not >CH₂; p is 0 or 1; R²¹ is independently hydrogen or a hydrocarbyl group, typically containing 1 to 150 carbon atoms, with the proviso that when R²¹ is hydrogen, p is 0, and q is more than or equal to 1; R²² is a hydrocarbyl group, typically containing 1 to 150 carbon atoms; R²³, R²⁴, R²⁵, R²⁶ and R²⁷ are independently hydrocarbyl groups; and R²⁸ is hydrogen or a hydrocarbyl group, containing 1 to 150 carbon atoms, or 4 to 32 carbon atoms, or 8 to 24 carbon atoms. In certain embodiments, the hydrocarbyl groups R²³, R²⁴, and R²⁵, may be linear or predominantly linear alkyl groups.

In certain embodiments, the ash-free friction modifier is a fatty ester, amide, or imide of various hydroxy-carboxylic acids, such as tartaric acid, malic acid lactic acid, glycolic acid, and mandelic acid. Examples of suitable materials include tartaric acid di(2-ethylhexyl) ester (i.e., di(2-ethylhexyl)tartrate), di(C₈-C₁₀) tartrate, di(C₁₂₋₁₅) tartrate, di-oleyl tartrate, oleyl tartrimide, and oleyl maleimide.

In certain embodiments, the ash-free friction modifier may be chosen from long chain fatty acid derivatives of amines, fatty esters, or fatty epoxides; fatty imidazolines such as condensation products of carboxylic acids and polyalkylene-polyamines; amine salts of alkylphosphoric acids; fatty alkyl tartrates; fatty alkyl tartrimides; fatty alkyl tartramides; fatty phosphonates; fatty phosphites; borated phospholipids, borated fatty epoxides; glycerol esters; borated glycerol esters; fatty amines; alkoxylated fatty amines; borated alkoxylated fatty amines; hydroxyl and polyhydroxy fatty amines including tertiary hydroxy fatty amines; hydroxy alkyl amides; metal salts of fatty acids; metal salts of alkyl salicylates; fatty oxazolines; fatty ethoxylated alcohols; condensation products of carboxylic acids and polyalkylene polyamines; or reaction products from fatty carboxylic acids with guanidine, aminoguanidine, urea, or thiourea and salts thereof.

Friction modifiers may also encompass materials such as sulfurized fatty compounds and olefins, sunflower oil or soybean oil monoester of a polyol and an aliphatic carboxylic acid.

In another embodiment the friction modifier may be a long chain fatty acid ester. In another embodiment the long chain fatty acid ester may be a mono-ester and in another embodiment the long chain fatty acid ester may be a triglyceride.

Molybdenum compounds are also known as friction modifiers. The exemplary molybdenum compound does not contain dithiocarbamate moieties or ligands.

Nitrogen-containing molybdenum materials include molybdenum-amine compounds, as described in U.S. Pat. No. 6,329,327, and organomolybdenum compounds made from the reaction of a molybdenum source, fatty oil, and a diamine as described in U.S. Pat. No. 6,914,037. Other molybdenum compounds are disclosed in U.S. Pub. No. 20080280795. Molybdenum amine compounds may be obtained by reacting a compound containing a hexavalent molybdenum atom with a primary, secondary or tertiary amine represented by the formula NR²⁹R³⁰R³¹, where each of R²⁹, R³⁰ and R³¹ is independently hydrogen or a hydrocarbyl group of 1 to 32 carbon atoms and wherein at least one of R²⁹, R³⁰ and R³¹ is a hydrocarbyl group of 4 or more carbon atoms or represented by the formula:

where R³² represents a chain hydrocarbyl group having 10 or more carbon atoms, s is 0 or 1, R³³ and/or R³⁴ represents a hydrogen atom, a hydrocarbyl group, an alkanol group or an alkyl amino group having 2 to 4 carbon atoms, and when s=0, both R³³ and R³⁴ are not hydrogen atoms or hydrocarbon groups.

Specific examples of suitable amines include monoalkyl (or alkenyl) amines such as tetradecylamine, stearylamine, oleylamine, beef tallow alkylamine, hardened beef tallow alkylamine, and soybean oil alkylamine; dialkyl(or alkenyl)amines such as N-tetradecylmethylamine, N-pentadecylmethylamine, N-hexadecylmethylamine, N-stearylmethylamine, N-oleylmethylamine, N-cocoyl methylamine, N-beef tallow alkyl methylamine, N-hardened beef tallow alkyl methylamine, N-soybean oil alkyl methylamine, ditetradecylamine, dipentadecylamine, dihexadecylamine, distearylamine, dioleylamine, bis(2-hexyldecyl)amine, bis(2-octyldodecyl)amine, bis(2-decyltetradecyl)amine, beef tallow dialkylamine, hardened beef tallow dialkylamine, and soybean oil dialkylamine; and trialk(en)ylamines such as tetradecyldimethylamine, hexadecyldimethylamine, octadecyldimethylamine, beef tallow alkyldimethylamine, hardened beef tallow alkyldimethylamine, soybean oil alkyldimethylamine, dioleylmethylamine, tritetradecylamine, tristearylamine, and trioleylamine. Suitable secondary amines have two alkyl (or alkenyl) groups with 14 to 18 carbon atoms.

Examples of the compound containing the hexavalent molybdenum atom include molybdenum trioxides or hydrates thereof (MoO₃.nH₂O), molybdenum acid (H₂MoO₄), alkali metal molybdates (Q₂MoO₄) wherein Q represents an alkali metal, such as sodium or potassium, ammonium molybdates ((NH₄)₂MoO₄ or heptamolybdate (NH₄)₆[Mo₇O₂₄].4H₂O), MoOCl₄, MoO₂Cl₂, MoO₂Br₂, Mo₂O₃Cl₆, and the like. Molybdenum trioxides or hydrates thereof, molybdenum acid, alkali metal molybdates and ammonium molybdates are often suitable because of their availability. In one embodiment, the lubricating composition comprises molybdenum amine compound.

Other suitable organomolybdenum compounds may be the reaction products of fatty oils, mono-alkylated alkylene diamines and a molybdenum source. Materials of this sort are generally made in two steps, a first step involving the preparation of an aminoamide/glyceride mixture at high temperature, and a second step involving incorporation of the molybdenum.

Examples of fatty oils that may be used include cottonseed oil, groundnut oil, coconut oil, linseed oil, palm kernel oil, olive oil, corn oil, palm oil, castor oil, rapeseed oil (low or high erucic acids), soyabean oil, sunflower oil, herring oil, sardine oil, and tallow. These fatty oils are generally known as glyceryl esters of fatty acids, triacylglycerols or triglycerides.

Examples of some mono-alkylated alkylene diamines that may be used include methylaminopropylamine, methylaminoethylamine, butylaminopropylamine, butylaminoethylamine, octylaminopropylamine, octylaminoethylamine, dodecylaminopropylamine, dodecylaminoethylamine, hexadecylaminopropylamine, hexadecylaminoethylamine, octadecyl-aminopropylamine, octadecylaminoethylamine, isopropyloxypropyl-1,3-diaminopropane, and octyloxypropyl-1,3-diaminopropane. Mono-alkylated alkylene diamines derived from fatty acids may also be used. Examples include N-coco alkyl-1,3-propanediamine (Duomeen®C), N-tall oil alkyl-1,3-propanediamine (Duomeen®T) and N-oleyl-1,3-propanediamine (Duomeen®O), all commercially available from Akzo Nobel.

Sources of molybdenum for incorporation into the fatty oil/diamine complex are generally oxygen-containing molybdenum compounds include, similar to those above, ammonium molybdates, sodium molybdate, molybdenum oxides and mixtures thereof. One suitable molybdenum source comprises molybdenum trioxide (MoO₃).

Nitrogen-containing molybdenum compounds which are commercially available include, for example, Sakuralube® 710 available from Adeka which is a molybdenum amine compound, and Molyvan® 855, available from R.T. Vanderbilt.

The nitrogen-containing molybdenum compound may be present in the lubricant composition at 0.005 to 2 wt. % of the composition, or 0.01 to 1.3 wt. %, or 0.02 to 1.0 wt. % of the composition. The molybdenum compound may provide the lubricant composition with 0 to 1000 ppm, or 5 to 1000 ppm, or 10 to 750 ppm 5 ppm to 300 ppm, or 20 ppm to 250 ppm of molybdenum.

L. Demulsifiers

Demulsifiers useful herein include trialkyl phosphates, and various polymers and copolymers of ethylene glycol, ethylene oxide, propylene oxide, and mixtures thereof.

M. Seal Swell Agents

Seal swell agents useful herein include sulfolene derivatives such as Exxon Necton-37™ (FN 1380) and Exxon Mineral Seal Oil™ (FN 3200).

N. TBN Boosters

Useful TBN boosters are anthranilate ester (esters of anthranilic acid) as described, for example, in U.S. Pub. No. 20140187458, such as decyl anthranilate.

Example Lubricating Compositions

An engine lubricant in different embodiments may have a composition as illustrated in Table 1. All additives are expressed on an oil-free basis.

The exemplary N-alkylated dianiline compound tends to be more effective in low magnesium lubricating compositions. In the lubricating composition, a ratio of calcium to magnesium by weight, may be at least 90:10 and in one embodiment, up to 10:90. Calcium can be provided by overbased detergents, such as calcium sulfonates, as discussed above. In one embodiment, the lubricating composition includes less than 500 ppm magnesium, or less than 200 ppm magnesium, or less than 100 ppm magnesium.

TABLE 1 Example Lubricating Composition Embodiments (wt. %) Additive A B C Example compound 0.1 to 5 0.2 to 2.5 0.3 to 1 Ashless antioxidant selected from a 0.0 to 5 0.1 to 2.5 0.3 to 1 diarylamine antioxidant, a phenolic antioxidant, and mixtures thereof Overbased Calcium Detergent(s) 0.1 to 8 0.3 to 6 1 to 5 Dispersant Viscosity Modifier(s) 0 to 5 0.05 to 4 0.1 to 2 Dispersants 0 to 12 1.5 to 8 0.5 to 6 Other Antioxidants 0.0 to 13 0.1 to 10 2.0 to 5 Other Detergents 0.1 to 8 0.3 to 6 1 to 5 Antiwear Agent(s) 0.1 to 10 0.1 to 5 0.3 to 2 Friction Modifier(s) 0.01 to 4 0.05 to 2 0.1 to 1 Viscosity Modifier(s), other than DVMs 0 to 10 0.5 to 8 1 to 6 Any Other Performance Additive 0 to 10 0 to 8 0 to 6 Oil of Lubricating Viscosity Balance Balance Balance to 100% to 100% to 100%

Use of the Lubricating Composition

The lubricating composition described herein may be used in a method for reducing deposit formation in an internal combustion engine. The internal combustion engine is lubricated with the lubricating composition.

The end use of the lubricating composition described herein includes use as a cylinder lubricant for an internal combustion engine, such as in a passenger car or a heavy, medium, or light duty diesel vehicle, but may also find use as an engine oil for 2-stroke marine diesel engines, small engines such as motorcycle and 2-stroke oil engines, as a driveline lubricant, including gear and automatic transmission oils, and for other industrial oils, such as hydraulic lubricants.

An exemplary method of lubricating a mechanical device, such as a passenger car engine cylinder, includes supplying the exemplary lubricating composition to the device.

Generally, the lubricating composition is added to the lubricating system of an internal combustion engine, which then delivers the lubricating composition to the cylinder of the engine, during its operation.

The internal combustion engine may be a gasoline fuelled engine, a diesel-fuelled engine, such as a 2-stroke marine diesel engine, or a natural gas fuelled engine, a mixed gasoline/alcohol fuelled engine, or a biodiesel fuelled engine. The internal combustion engine may be a 2-stroke or 4-stroke engine.

In one embodiment the disclosed technology provides a method of lubricating a 2-stroke or 4-stroke internal combustion engine comprising supplying to the internal combustion engine a lubricating composition as disclosed herein.

The internal combustion engine may be a passenger car internal combustion engine. The passenger car internal combustion engine may have a reference mass not exceeding 2610 kg. The passenger car engine may be operated on unleaded gasoline. Unleaded gasoline is well known in the art and is defined by British Standard BS EN 228:2008 (entitled “Automotive Fuels—Unleaded Petrol—Requirements and Test Methods”). The internal combustion engine may also be a heavy duty diesel internal combustion engine. The heavy duty diesel internal combustion engine may have a “technically permissible maximum laden mass” over 3,500 kg. The engine may be a compression ignition engine or a positive ignition natural gas (NG) or LPG (liquefied petroleum gas) engine.

The lubricating composition may be suitable for use as a cylinder lubricant irrespective of the sulfur, phosphorus or sulfated ash (ASTM D-874) content of the fuel. The sulfur content of the lubricating composition, which is particularly suited to use as an engine oil lubricant, may be 1 wt. % or less, or 0.8 wt. % or less, or 0.5 wt. % or less, or 0.3 wt. % or less. In one embodiment, the sulfur content may be in the range of 0.001 wt. % to 0.5 wt. %, or 0.01 wt. % to 0.3 wt. %. The phosphorus content may be 0.2 wt. % or less, or 0.12 wt. % or less, or 0.1 wt. % or less, or 0.085 wt. % or less, or 0.08 wt. % or less, or even 0.06 wt. % or less, 0.055 wt. % or less, or 0.05 wt. % or less. In one embodiment, the phosphorus content may be 100 ppm to 1000 ppm, or 200 ppm to 600 ppm. The total sulfated ash content may be 2 wt. % or less, or 1.5 wt. % or less, or 1.1 wt. % or less, or 1 wt. % or less, or 0.8 wt. % or less, or 0.5 wt. % or less, or 0.4 wt. % or less. In one embodiment, the sulfated ash content may be 0.05 wt. % to 0.9 wt. %, or 0.1 wt. % to 0.2 wt. % or to 0.45 wt. %.

Without intending to limit the scope of the exemplary embodiment, the following examples illustrate preparation and evaluation of example compounds.

EXAMPLES

All reactants and additives are expressed on an oil-free basis.

Example 1: Synthesis of 4,4′-cyclohexylmethylenedianiline (CY-MDI)

4,4′-methylenedianiline (MDA) (1 eq.), cyclohexanone (2.1 eq.) and acetic acid (0.05 eq.) are charged to a flask with toluene and heated to reflux with removal of water. Once imine formation is complete, the toluene and residual acetic acid are removed by vacuum. The resulting imine is dissolved in methanol and cooled to less than 10° C. using an ice bath. Sodium borohydride (2.2 eq.) is added portion-wise, keeping the reaction temperature below 15° C. The solution is then allowed to warm to room temperature and stirred for an additional 2 hours. Once reduction is complete, the mixture is quenched with water and the product is extracted with ethyl acetate. No further purification is needed. The reaction results in the formation of compound A-1 shown in TABLE 2.

Example 2: Synthesis of 4,4′-2-ethylhexylmethylenedianiline (EHL-MDI)

The process of Example 1 is repeated, using 2-ethylhexanal (2.1 eq.) in place of cyclohexanone as the ketone. The reaction results in the formation of compound A-2 shown in TABLE 2:

Using the method of Examples 1 and 2, with the product being either collected by filtration or by extraction with ethyl acetate, the products shown in TABLE 2 are formed using the following amines and ketones/aldehydes:

TABLE 2 Diamine Compounds Ketone/ Example Aldehyde Amine A-1

cyclohexanone MDA A-2

2-ethylhexanal MDA A-3

3-pentanone MDA A-4

4-methyl cyclohexanone MDA A-5

methyl isobutyl ketone MDA A-6

4-tert-butyl cyclohexanone MDA A-7

isophorone MDA A-8

3,3,5-trimethyl cyclohexanone MDA A-9

acetophenone MDA A-10

benzophenone MDA A-11

benzaldehyde MDA A-12

cyclohexanone 2,4,6- trimethyl- aniline A-13

4-methyl cyclohexanone 2,4,6- trimethyl- aniline

Example 3: Lubricating Compositions

The N,N′-dialkylmethylenedianilene compounds prepared according to Examples 1 and 2 are evaluated in various formulations.

A. Higher Internal Combustion Engine Lubricants

Lubricating compositions suitable as 5W-30 engine lubricants are prepared using a baseline formulation as shown in TABLE 3. All concentrations are on an oil free (i.e., active basis).

TABLE 3 Baseline Lubricating Composition B1 Component Baseline B1 Base Oil Balance to 100% Calcium alkylsulfonates (overbased detergent) 0.9 Secondary Zinc dialkyldithiophosphate (ZDDP) 0.86 Diarylamine antioxidant¹ 0.9 Phenol antioxidant² 0.35 Polyisobutylene succinimide dispersant³ 2.12 Ethylene-propylene copolymer (viscosity modifier) 0.7 Additional performance additives (friction modifiers, 0.51 corrosion inhibitors, foam inhibitors, pour point depressants, etc.) % Phosphorus 0.075 ¹Dinonylated diphenylamine ²Alkyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate ³Combination of Polyisobutylene succinimide dispersants with Mn ranging from 1600-2300

The alkylated dianilines of Examples 1 and 2 are added to the baseline composition, as shown in TABLE 4, to form lubricating compositions L1 and L2, respectively.

TABLE 4 Lubricating Oil Composition Formulations Composition B1 L1 L2 B1 100 99.5 99.5 A-1 0.5 A-2 0.5 % Phosphorus 0.075 0.075 0.075 D2896 TBN (mg KOH/kg) 7.5 9.1 8.7

Lubricating compositions B1, L1, and L2 are evaluated in the following oxidation bench tests:

1. Impact on thin-film antioxidancy: The Pressure Differently Scanning calorimeter (PDSC) test measures the compositions' oxidative induction time (OIT). This is a standard test procedure in the lubricating oil industry, based on CEC L-85 T-99. In this testing the lubricating composition is heated to an elevated temperature, typically about 25° C. below the average decomposition temperature for the sample being tested (in this case 215° C. at 690 kPa), and the time to when the composition begins to decompose is measured. The longer the test time, reported in minutes, the better the oxidative stability of the composition and the additives present within it.

2. Deposits (MHT TEOST): determined according to ASTM D7097-09. The MHT TEOST method evaluates deposit formation at temperatures closely related to those of the piston ring zone in reciprocating engines. An organo-metallic catalyst mixture of a predetermined concentration equaling approximately 8.5 g is circulated for 24 hrs over a wire-wound depositor rod at 285° C. along with 10 ml/min of air. The depositor rod is weighed before test and after testing. Any post-test deposits collected after washing the rod along with rod deposits equals total deposits. In the MHT TEOST, a lower amount of deposit indicates better deposit control performance.

The results obtained are shown in TABLE 5.

TABLE 5 Oxidation Results for Lubricating Oil Composition Formulations Example PDSC OIT min L-85-99 OIT min MHT TEOST mg B1 67 80 42 L1 109 97 13 L2 84 82 18

The results shown in TABLE 5 suggest that the lubricating compositions (L1 and L2) (for example, an internal combustion engine lubricant) containing the alkylated dianilines of Examples 1 and 2 provide exceptional antioxidancy performance as well as unexpected deposit control performance when compared with the baseline formulation (B1).

B. Low-Phosphorus Internal Combustion Engine Lubricants

Lubricating compositions suitable as 5W-30 engine lubricants are prepared using a baseline formulation (B2) as shown in TABLE 6. All concentrations are on an oil-free (i.e., active) basis.

TABLE 6 Baseline lubricating composition B2 Component Baseline B2 Base Oil Balance to 100% Calcium alkylsulfonates (overbased detergent) 0.9 Zinc dialkyldithiophosphate (ZDDP) 0.43 Antioxidants ¹ 1.73 Polyisobutylene succinimide dispersant² 2.65 Polymeric Viscosity Modifier 0.7 Additional performance additives (friction modifiers, 0.61 corrosion inhibitors, foam inhibitors, pour point depressants, etc.) % Phosphorus 0.038 ¹ Combination of diarylamine and hindered phenol ²Combination of Polyisobutylene succinimide dispersants with Mn ranging from 1600-2300

The diamines A-1, A-3, and A-4 are added to the baseline composition B1 in the amounts shown in TABLE 7, to form lubricating compositions L3, L4, and L5. A further lubricating composition (C1) is prepared with an aminic antioxidant.

TABLE 7 Lubricating Oil Composition Formulations Composition B2 L3 L4 L5 C1 B2 100 99.5 99.5 99.5 99.5 A-1 0.5 A-4 0.5 A-3 0.5 Aminic AO 0.5 % Phosphorus 0.038 0.038 0.038 0.038 0.038 TBN, mg of KOH/g 8.7 9.6 9.5 9 (D2896)

Lubricating compositions B2, L3, L4, L5, and C1 are evaluated in the oxidation bench tests, as described above. The results obtained are shown in TABLE 8.

TABLE 8 Oxidation Results for Lubricating Oil Composition Formulations Example PDSC OIT min L-85-99 OIT min MHT TEOST mg B2 65 104 39 L3 94 125 16 L4 102 160 15 L5 87 108 16 C1 70 105 40

The results shown in TABLE 8 suggest that the exemplary lubricating compositions (L3, L4, and L5) (for example, an internal combustion engine lubricant) containing the alkylated dianilines A-1, A-3, and A-4 provide exceptional antioxidancy performance as well as unexpected deposit control performance when compared with the baseline formulation (B2), indicating that the exemplary alkylated dianilines are very efficient in low phosphorus formulations. Additionally, 0.5% of these alkylated dianilines provides a much more significant performance enhancement to the baseline formulation in both the PDSC and the MHT TEOST tests than the addition of a further 0.5% of aminic antioxidant (C1).

C. Internal Combustion Engine Lubricants

Lubricating compositions suitable as 15W-40 engine lubricants are prepared using a baseline formulation (B3) as shown in TABLE 9. All concentrations are on an oil-free (i.e., active basis).

TABLE 9 Baseline lubricating composition B3 Component Baseline B3 Base Oil Balance to 100% Calcium alkylsulfonate and calcium sulfur-coupled 2.7 alkylphenol (overbased detergent) Zinc dialkyldithiophosphate (ZDDP) 1.15 Antioxidants (combination of diarylamine and 1.25 hindered phenol) 2200 Mn polyisobutylene succinimide, TBN ~55 3.6 (ashless dispersant) Polymeric Viscosity Modifier 0.9 Additional performance additives (corrosion inhibitor, 0.86 foam inhibitors, pour point depressant, and surfactant etc.) % Phosphorus 0.11

The diamines A-1 and A-2 are added to the baseline composition B3 in the amounts shown in TABLE 10, to form lubricating compositions L6 and L7.

TABLE 10 Lubricating Oil Composition Formulations Composition B3 L6 L7 B3 100 99.5 99.5 A-2 0.5 A-1 0.5 % Phosphorus 0.11 0.11 0.11 TBN mg of KOH/g (D2896) 11.8 12.7 13.2

Lubricating compositions B3, L6, and L7 are evaluated in the oxidation bench tests, as described above. The results obtained are shown in TABLE 11.

TABLE 11 Oxidation Results for Lubricating Oil Composition Formulations Example PDSC OIT min MHT TEOST mg B3 84 20 L6 87 5.5 L7 89 4.6

The results shown in TABLE 11 suggest that the exemplary lubricating compositions (L6 and L7) (for example, an internal combustion engine lubricant) containing the alkylated dianilines A-1 and A-2 provide exceptional antioxidancy performance as well as unexpected deposit control performance when compared with the baseline formulation (B3), indicating that the exemplary alkylated dianilines are very efficient in these formulations.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. By predominantly hydrocarbon character, it is meant that at least 70% or at least 80% of the atoms in the substituent are hydrogen or carbon.

Examples of hydrocarbyl groups include:

(i) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form a ring);

(ii) substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon nature of the substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);

(iii) hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, may contain other than carbon in a ring or chain otherwise composed of carbon atoms.

Representative alkyl groups include n-butyl, iso-butyl, sec-butyl, n-pentyl, amyl, neopentyl, n-hexyl, n-heptyl, secondary heptyl, n-octyl, secondary octyl, 2-ethyl hexyl, n-nonyl, secondary nonyl, undecyl, secondary undecyl, dodecyl, secondary dodecyl, tridecyl, secondary tridecyl, tetradecyl, secondary tetradecyl, hexadecyl, secondary hexadecyl, stearyl, icosyl, docosyl, tetracosyl, 2-butyloctyl, 2-butyldecyl, 2-hexyloctyl, 2-hexydecyl, 2-octyldecyl, 2-hexyldodecyl, 2-octyldodecyl, 2-decyltetradecyl, 2-dodecylhexadecyl, 2-hexyldecyloctyldecyl, 2-tetradecyloctyldecyl, monomethyl branched-isostearyl, and the like.

Representative aryl groups include phenyl, toluyl, xylyl, cumenyl, mesityl, benzyl, phenethyl, styryl, cinnamyl, benzhydryl, trityl, ethylphenyl, propylphenyl, butylphenyl, pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, benzylphenyl, styrenated phenyl, p-cumylphenyl, α-naphthyl, β-naphthyl groups, and mixtures thereof.

Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents, such as pyridyl, furyl, thienyl and imidazolyl. In general, no more than two, and in one embodiment, no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group. In some embodiments, there are no non-hydrocarbon substituents in the hydrocarbyl group.

Representative aliphatic groups may contain 4 to 14 carbon atoms, 6 to 12 carbon atoms, or 8 to 10 carbon atoms. Examples of suitable alkyl groups include butyl, isobutyl, pentyl, isopentyl, neopentyl, hexyl, amyl, heptyl, octyl, iso-octyl, 2-ethylhexyl, nonyl, decyl, iso-decyl, undecyl, dodecyl, 2-propylheptyl, tridecyl, isotridecyl, tetradecyl, 4-methyl-2-pentyl, propyl heptyl, and combinations thereof.

Hydrocarbylene groups are the divalent equivalents of hydrocarbyl groups, such as alkylene groups.

Each of the documents referred to above is incorporated herein by reference. Except in the Examples, or where otherwise explicitly indicated, all numerical quantities in this description specifying amounts of materials, reaction conditions, molecular weights, number of carbon atoms, and the like, are to be understood as modified by the word “about.” Unless otherwise indicated, each chemical or composition referred to herein should be interpreted as being a commercial grade material which may contain the isomers, by-products, derivatives, and other such materials which are normally understood to be present in the commercial grade. However, the amount of each chemical component is presented exclusive of any solvent or diluent oil, which may be customarily present in the commercial material, unless otherwise indicated. It is to be understood that the upper and lower amount, range, and ratio limits set forth herein may be independently combined. Similarly, the ranges and amounts for each element of the invention may be used together with ranges or amounts for any of the other elements.

It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. 

1. A lubricating composition comprising: a) an oil of lubricating viscosity; b) an N-alkylated dianiline compound; and c) an ashless antioxidant selected from a diarylamine antioxidant, a phenolic antioxidant, and combinations thereof, and d) an overbased calcium detergent; wherein the lubricating composition comprises less than 0.15 weight percent of phosphorus; and wherein the N-alkylated dianiline is an N,N′-alkylated dianiline compound represented by the formula:

wherein R¹ and R² are independently selected from alkyl groups of 1 to 24 carbon atoms; R³ and R⁴ are independently selected from hydrocarbyl groups of 1 to 6 carbon atoms; each n is from 0 to 3, and X represents a C₁-C₃ alkylene group.
 2. (canceled)
 3. The lubricating composition of claim 1, wherein the lubricating composition has a TBN of at least 4 mg KOH/g, as measured in accordance with ASTM D-2896.
 4. (canceled)
 5. The lubricating composition of claim 1, wherein at least one of R¹ and R² includes a cyclohexyl group.
 6. (canceled)
 7. The lubricating composition of claim 1, wherein the N-alkylated dianiline compound is at least 0.10 weight percent of the lubricating composition.
 8. (canceled)
 9. (canceled)
 10. The lubricating composition of claim 1, wherein X is a methylene group.
 11. The lubricating composition of claim 1, wherein the N-alkylated dianiline compound is represented by the formula:

wherein R¹ and R² are independently selected from alkyl groups of 1 to 24 carbon atoms.
 12. The lubricating composition of claim 11, wherein the N-alkylated dianiline compound is represented by the formula:


13. The lubricating composition of claim 1, wherein the N-alkylated dianiline compound is selected from the group consisting of:

and mixtures thereof.
 14. The lubricating composition of claim 13, wherein the N-alkylated dianiline compound is selected from 4,4′-2-ethylhexylmethylenedianiline, 4,4′-cyclohexylmethylenedianiline, and mixtures thereof.
 15. The lubricating composition of claim 1, wherein the oil of lubricating viscosity is at least 40 weight percent of the lubricating composition.
 16. The lubricating composition of claim 1, wherein the ashless antioxidant is at least 0.1 weight % of the lubricating composition.
 17. The lubricating composition of claim 1, wherein a ratio of the ashless antioxidant to the N-alkyl dianiline compound is from 20:1 to 1:20.
 18. The lubricating composition of claim 1, wherein the ashless antioxidant comprises at least one of: a phenolic ester and a diarylamine; and a sulfurized olefin.
 19. (canceled)
 20. The lubricating composition of claim 1, wherein the overbased calcium detergent is selected from sulfonates, non-sulfur containing phenates, sulfur containing phenates, salixarates, salicylates, mixtures thereof, and borated equivalents thereof.
 21. The lubricating composition of claim 1, wherein the overbased calcium detergent is present in an amount to deliver at least 2 mg KOH/g of total base number (TBN), as measured in accordance with ASTM D-2896, to the composition.
 22. The lubricating composition of claim 1, wherein the overbased calcium detergent is least 0.01 wt. % of the lubricating composition.
 23. The lubricating composition of claim 1, wherein a ratio of calcium to magnesium in the lubricating composition, by weight, is at least 9:10.
 24. The lubricating composition of claim 1, further comprising a polyolefin succinimide dispersant, wherein a polyolefin group of the polyolefin succinimide dispersant has a number average molecular weight of at least
 300. 25. The lubricating composition of claim 1, further comprising a zinc dialkyldithiophosphate.
 26. The lubricating composition of claim 1, wherein the lubricating composition comprises at least 0.02 weight percent of phosphorus.
 27. (canceled)
 28. A method for reducing deposit formation in an internal combustion engine comprising lubricating the internal combustion engine with a lubricating composition comprising: a) an oil of lubricating viscosity; b) an N-alkylated dianiline compound; c) an ashless antioxidant selected from a diarylamine antioxidant, a phenolic antioxidant, and combinations thereof, and d) an overbased calcium detergent; wherein the lubricating composition comprises less than 0.15 weight percent of phosphorus; and wherein the N-alkylated dianiline is an N,N′-alkylated dianiline compound represented by the formula:

wherein R¹ and R² are independently selected from alkyl groups of 1 to 24 carbon atoms; R³ and R⁴ are independently selected from hydrocarbyl groups of 1 to 6 carbon atoms; each n is from 0 to 3, and X represents a hydrocarbylene group.
 29. (canceled)
 30. A method for forming a lubricating composition comprising: forming an N,N′-alkylated dianiline compound represented by the formula:

wherein R¹ and R² are independently selected from alkyl groups of 1 to 24 carbon atoms; R³ and R⁴ are independently selected from hydrocarbyl groups of 1 to 6 carbon atoms; each n is from 0 to 3, and X represents a hydrocarbylene group; and combining the N-alkylated dianiline compound with an oil of lubricating viscosity and at least one of: an ashless antioxidant selected from a diarylamine antioxidant, a phenolic antioxidant, and combinations thereof, and an overbased calcium detergent; whereby the lubricating composition comprises less than 0.15 weight percent of phosphorus.
 31. The lubricating composition of claim 1, wherein R¹ and R² are independently selected from alkyl groups of at least 4 carbon atoms. 